Article Figures & SI

Figures

Our design strategy for ROS-sensitive imaging probes. The designed probe CRANAD-61, on reaction with ROS, produces a significant Em wavelength shift, which can be used for identifying active plaques and CAAs via dual-color two-photon microscopic imaging. The shifting can also lead to a visible to invisible transformation in an NIR window (640–900 nm), as CRANAD-5, the product of the ROS reaction, is invisible with an NIR camera. This transformation could be harnessed for a whole-brain NIRF imaging to quantify the total relative ROS concentrations in AD brains.

In vitro testing of CRANAD-61 with various ROS. (A) Fluorescence intensity (F.I.) increases at 570 nm after CRANAD-61 incubation with ROS at different time points (Ex = 460 nm). (B) Spectral changes of CRANAD-61 after incubating with H2O2 at different time points. Note the increase in intensity at 570 nm and decrease in intensity at 810 nm (Ex = 675 nm). (C) Concentration-dependent intensity change of CRANAD-61 with ROS (H2O2 as a representative).

In vivo dual-color two-photon imaging of CAA (A, A′, A′′) and plaques (C, C′, C′′) of APP/PS1 mice after i.v. injection of CRANAD-61 at different time points (5, 20, and 60 min), indicating that CRANAD-61 was able to cross BBB and specifically label plaques and CAAs. CRANAD-61 initially binds to amyloid with red fluorescence Em. Over the time of imaging, intensity in the red fluorescence channel decreased, while intensity in the green fluorescence channel increased, indicating ongoing conversion of CRANAD-61 into CRANAD-5 (B and D; n = 10 imaged amyloid deposits for each group; data shown as an individual point). Wilcoxon matched pairs signed rank tests were used for statistical testing between different time points. A P < 0.05 level was regarded as statistically significant. The asterisk indicates that one plaque showed no apparent conversion. a.u., arbitrary unit. (E) Example of an amyloid plaque colabeled with FSB and CRANAD-61 imaged in vivo at high magnification. The image was superimposed from acquisition at 800-nm Ex (FSB; blue channel) and 900-nm Ex (CRANAD-61; red and green channels). A heat map of the fluorescence intensity ratio between green and red channels (E′) indicated microregions in the plaque with a higher conversion rate (arrow). (F) Representative images of one plaque that showed no decrease in the red fluorescence intensity at 5, 20, or 60 min (arrows; F, F′, F′′), while the free dye in the blood was significantly reduced.

In vivo NIRF imaging with CRANAD-61. (A) Representative images of WT and APP/PS1 mice after i.v. injection with CRANAD-61 at 30, 60, 120, and 240 min. (B) Quantification of images in A. Note that NIRF signals from WT are significantly higher than that from APP/PS1 mice. **P < 0.01, ***P < 0.005. (C) Changes of the NIRF signal ratio R(AD/WT) [R(AD/WT) = F(AD)/F(WT)] from 30 to 240 min. The negative slope suggested that the disappearance rate of the CRANAD-61 signal in AD brains was faster than in WT brains. (D) Changes of relative ROS levels in APP/PS1 mice of different ages. There was a dramatic increase of ROS levels from age 4 to 12 mo old.

Bacteria could help tackle the growing mountains of e-waste that plague the planet. Although researchers are a long way from optimizing the approach, some are already confident enough to pursue commercial ventures.

Holographic acoustic tweezers, in which ultrasonic waves produced by arrays of sound emitters are used to individually manipulate up to 25 millimeter-sized particles in three dimensions, could be used to create 3D displays consisting of levitating physical voxels.